Rendering stuck at 99%
Render your animation to png, not as FFMPEG. So you will have your single frame pictures on your hard disc. You can then make a movie out of it with video editing from Blender. If you are just missing one frame of your animation, you still have a 99% of a movie - instead of nothing.
If you want more help you should provide us your .blend file.
Reason for being stuck can be a lot. From you machine has to low memory until it is not stuck, but just calculating ...